Plastic blocks for use in erecting walls whether they may be decorative or otherwise, are becoming more popular. Such plastic blocks are known and there are patents covering various types of blocks and designs with respect to wall construction using plastic blocks. Several patents in the area of plastic blocks are U.S. Pat. No. 4,632,589; U.S. Pat. No. 4,891,925; U.S. Pat. No. 4,793,104 and U.S. Pat. No. 5,033,245.
In comparison to glass blocks, plastic blocks are inexpensive, easily produced and provide aesthetically appealing modular wall structures both for interior and exterior decorative walls. Plastic building blocks provide a number of advantages over conventional glass building blocks, such as, they are lighter in weight, have better impact resistance, generally have better optical clarity, are generally less expensive to make and may be easier to incorporate decorative features in a plastic block, and allows an interlocking system as part of the plastic block.
Several of the above patents disclose plastic blocks and these are U.S. Pat. Nos. 4,891,925 and 5,033,245. U.S. Pat. No. 4,891,925 discloses a plastic block having special inter-connecting means without the need for motor or adhesive joining of the blocks. The blocks of the reference are joined by a spanning member having ends adjusted for engaging in cavities of two adjacent blocks which can then be connected to form a unified straight wall structure. However, the patent discloses using grouting, once a partition is erected, to cover the recessed spacing flanges between the faces of the blocks (col. 3, lines 54-55).
U.S. Pat. No. 5,033,245 is directed to decorative architectural building blocks which are generally a plurality of halves joined together along a seam to form a hollow block. The outer surfaces may be surfaced with a transparent, abrasion, chemical and/or ultraviolet light resistant coating. The blocks are assembled and joined together adhesively (Col. 3 lines 1-10), with such adhesive as RTV silicones or other adhesives which can be utilized in place of conventional motor (Col. 1, lines 29-32).